Diagnostic test kits have been developed for detection or analysis of target biological and environmental species in samples. Such test kits provide convenience since they may be used at a point of care such as a home, a medical facility, or elsewhere. For example, in a work place, a drug test kit can be used to detect one or more specific drugs or drug metabolites in a sample from an employee, a potential employee, or any other person that has agreed to be tested. Diseases, blood chemistry, DNA sequencing, and conditions such as pregnancy can similarly be quickly and conveniently detected using diagnostic test kits at home or wherever the test is desired.
Many diagnostic tests employ binding assay techniques. In a typical binding assay, a liquid sample is introduced to a flow matrix, e.g., into a test strip, where a labeling substance such as an antibody with an attached dye or florescent material binds to the target species. The complex thus created then flows to an indicator region that is treated to capture and hold the specific complex containing the target species and the labeling substance. The presence of the target species can then be detected through a change in the properties in the indicator region. For example, an accumulation of dye causing the indicator region to change color marks the presences of the target species in the sample.
Human observation has traditionally been used to determine the test results indicated by the change or lack of change in indicators of a diagnostic test kit. However, automated or electronic test evaluation may more reliably provide results, and integrated test systems or ICs are sought to provide test results without requiring human judgment. Such test systems would ideally be efficient and low cost for economic use in the widest variety of test situations.